This application relates to a molded plastic intake manifold wherein entry ports are formed within a separate runner such that the ports can be formed as close as possible to an idealized configuration.
Intake manifolds receive and distribute air to a number of cylinders within a vehicle engine. Historically, the intake manifold has been formed of metal. More recently, manifolds have been molded from plastics. One portion of the intake manifolds that is the subject of much design effort is the configuration of the entry ports leading from the manifold into engine cylinders. The entry ports typically have a closely designed curved surface intended to smoothly guide airflow into the engine cylinders.
The prior art formed the entry ports and the overall manifold body as a single molded part. It is difficult to achieve entry ports having the exact desired shape from a single molded part.
In a preferred embodiment of this invention, a molded plastic intake manifold is formed having a main inlet manifold body formed as a first part, and entry ports molded as a separate part. Preferably, the entry ports are formed in a runner which creates a number of the entry ports with a single part. The runner and the main body part are connected together to form the manifold. Since the runner is a relatively small and relatively flat item, the configuration of the entry ports can be closely controlled. Entry ports having the exact desired configuration can be achieved.
In one embodiment, the entry ports are formed in a runner including half portions of the ports. The other half of the port is formed within the main manifold body. One disclosed embodiment includes two separate runners, with the two separate runners positioned on opposed sides of the main manifold body.
In a more preferred embodiment, the runner has connecting webs connecting the runners on each side of the manifold. Further, the runners preferably define the entire entry port.
The runners may be pinned to the main manifold body, and then welded. In the preferred embodiment, the runner rests on a ledge on the manifold body before being welded. Although plastic welding is the preferred method of attaching the two, other attachment methods may be utilized.